In mathematics, a function f of n variables

x₁, ..., x_n

is a Chisini mean if for every vector

<x₁ ... x_n>,

there exists a unique M such that

f(M,M, ..., M) = f(x₁,x₂, ..., x_n).

The arithmetic, harmonic, geometric and quadratic means are all Chisini means, as are the weighted variants thereof.

Reference

They were introduced by Oscar Chisini, in the paper Chisini, O. "Sul concetto di media." Periodico di Matematiche 4, 106-116, 1929.